Abstract
Background: Down syndrome (DS) is associated with poor language skills that seem disproportionate to general nonverbal ability, but the nature and causes of this deficit are unclear. We assessed how individuals with DS understand complex linguistic constructions, and considered how cognitive ability, memory and hearing level impact the ability of those with DS to process these sentence types. Methods: There were three groups participating in the study: children with DS (n = 33) and two control groups composed of children with cognitive impairment of unknown aetiology (CI) (n = 32) and children with typical development (n = 33). Both groups were matched to those with DS on cognitive ability. Using a newly devised animation task, we examined how well individuals with DS (n = 33) could understand relative clauses, complement clauses and adverbial clauses compared to children with CI and typically developing controls. Participants also completed the Test for the Reception of Grammar-2, three measures of memory (forward and backward digit recall, visuo-spatial memory) and a hearing screen. Results: Results indicated that (1) with the exception of intransitive subject relative clauses, children with DS performed at floor on all other complex sentences, (2) they performed at a significantly lower level than both control groups, and (3) DS status accounted for a significant proportion of the variance over and above memory skills. Conclusions: Our findings suggest that children with DS have a disproportionate difficulty understanding complex sentences compared to two control groups matched on mental age. Furthermore, their understanding of syntax is not completely explained by poor cognitive or memory skills, rather it appears to be a specific deficit that may distinguish children with DS from other neurodevelopmental disorders.
Highlights
Down syndrome (DS) is the most common genetic cause of intellectual disability
This was in stark contrast to the two control groups, the majority of whom performed above chance level (74%) in the CI group and all of whom performed above chance in the typically developing (TD) group
In summary, our findings suggest that despite using a method of assessment designed to minimise non-linguistic demands, children with DS have a disproportionate difficulty understanding complex sentences compared to two control groups matched on mental age
Summary
Down syndrome (DS) is the most common genetic cause of intellectual disability. A diagnosis of DS is given when an error in cell development results in an extra copy of chromosome 21, so there are 47 chromosomes rather than the usual 46. Language difficulties in children with DS are well documented, those affecting vocabulary, phonology, morphology, and simple sentence structures (Dodd & Thomspson, 2001; Eadie et al, 2002; Laws & Bishop, 2003; Price et al, 2007). Information regarding these children’s understanding of complex syntax is very limited. It would be useful to give a sentence or two summarising whether the authors think Table 1 does show a unique profile of language for those with DS or not. It might be useful to flag up the complexities of WM here? p.5 I expected to see Hick et al (2005) here (visual STM =TD >DLD and Verbal STM=DLD p.5 Should read ‘(Frizelle et al 2018a)’ – no gap between 2018 and a. p.5 It would have been helpful to have some justification for the prediction that pretend would be easy and think difficult. p.6 Hypothesis 4 includes working memory even though backward span was included as a STM task
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
